The bank disclosed in regulatory filings that Mr Muriuki’s stake rose to 1.96 percent (114.9 million shares) in August from 1.77 percent (103.8 million shares) in February.

He has previously raised and lowered his stake in Co-op Bank in trades that indicate buying when the stock is cheap and taking profits in strong markets.

The latest purchases, for instance, came after a significant decline in the lender’s share price. Co-op Bank stock traded at highs of Sh16 on February 1 and fell to lows of Sh11.5 on August 21, according to market data. The share price decline was largely due to a general bear run, which had gripped the Nairobi bourse, offering long-term investors an opportunity to buy stocks at relatively cheaper levels.

Co-op Bank’s share price has since rallied, closing at Sh16.05 on Friday. The lender is among the beneficiaries of increased demand for bank shares following the recent scrapping of lending rate controls.

The share purchases and the price jump has lifted the market value of Mr Muriuki’s stake to Sh1.8 billion. Mr Muriuki has previously said his ownership should be seen as a sign of confidence in the bank.

He has remained the single largest individual investor in Co-op Bank since the company went public in 2008.

He is followed by billionaire investor Baloobhai Patel who holds a 0.45 percent equity (26.4 million shares) valued at Sh423 million. Co-op Bank and other lenders are expected to record higher lending margins in the coming years following the recent scrapping of rate caps.

The return to free-floating rates is also expected to incentivise banks to lend more to the private sector, having the discretion to charge relatively higher rates on loans to riskier borrowers.

Co-op Bank reported a 5.5 percent increase in net earnings in the nine months ended September, helped by a surge in non-interest income. Its net profit in the review period stood at Sh10.8 billion compared to Sh10.3 billion a year earlier. Its income from transactions rose by a third to Sh14 billion and compensated for a marginal decline in interest income.